Problem: Takahashi loves sorting.

He has a permutation (p_1,p_2,...,p_N) of the integers from 1 through N. Now, he will repeat the following operation until the permutation becomes (1,2,...,N):

* First, we will define high and low elements in the permutation, as follows. The i-th element in the permutation is high if the maximum element between the 1-st and i-th elements, inclusive, is the i-th element itself, and otherwise the i-th element is low.
* Then, let a_1,a_2,...,a_k be the values of the high elements, and b_1,b_2,...,b_{N-k} be the values of the low elements in the current permutation, in the order they appear in it.
* Lastly, rearrange the permutation into (b_1,b_2,...,b_{N-k},a_1,a_2,...,a_k).



How many operations are necessary until the permutation is sorted?

Constraints

* 1 ≤ N ≤ 2×10^5
* (p_1,p_2,...,p_N) is a permutation of the integers from 1 through N.

Input

Input is given from Standard Input in the following format:


N
p_1 p_2 ... p_N


Output

Print the number of operations that are necessary until the permutation is sorted.

Examples

Input

5
3 5 1 2 4


Output

3


Input

5
5 4 3 2 1


Output

4


Input

10
2 10 5 7 3 6 4 9 8 1


Output

6

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;
const int N=200005;
int p[N],n,x;
int main(){
	scanf("%d",&n);
	for (int i=1;i<=n;i++){
		scanf("%d",&x);
		p[x]=i;
	}
	int now=n-1;
	while (now&&p[now]<p[now+1])now--;
	if (!now){
		puts("0");
		return 0;
	}
	int ans=1,pre=now+1;
	for (;now;now--){
		if (p[pre]<=p[now]&&p[now]<=p[now+1])continue;
		if (p[now]<=p[now+1]&&p[now+1]<=p[pre])continue;
		if (p[now+1]<=p[pre]&&p[pre]<=p[now])continue;
		ans++;pre=now+1;
	}
	printf("%d",ans);
	return 0;
}